Luciana Rocha de Moura Estevão

Effect of clays on the fire-retardant properties of a polyethylenic copolymer containing intumescent formulation

Abstract Organophilic clay particles were added to a standard intumescent formulation and, since the role of clay expansion or intercalation is still a matter of much controversy, several clays with varying degrees of interlayer distances were evaluated. The composites were obtained by blending the nanostructured clay and the intumescent system with a polyethylenic copolymer. The flame-retardant properties of the materials were evaluated by the limiting oxygen index (LOI), the UL-94 rating and thermogravimetric analysis (TGA). The results showed that the addition of highly expanded clays to the ammonium polyphosphate and pentaerythritol formulation does not significantly increase the flame retardancy of the mixture, when measured by the LOI and UL-94. However, when clays with smaller basal distances were added to the intumescent formulation, a synergistic effect was observed. In contrast, the simple addition of clays to the copolymer, without the intumescent formulation, did not increase the fire retardance of the materials.

Development of Polyurethane Antimicrobial Composites Using Waste Oil Refinery Catalyst

Waste oil refinery catalyst from the FCC unit was tested as a possible additive for the production of polymeric composites with antimicrobial properties. The effect of the silver ion on the growth inhibition of bacteria (E. coli and S. aureus), mold (A. niger), and yeasts (C. tropicalis and Cr. humicolus) was studied. The catalyst was ion exchanged with silver nitrate and incorporated into thermoplastic polyurethanes with different hardness ratings. The materials produced were submitted to microbial testing both in solid and liquid media, and the effect of the polymeric matrix on the rate of silver ion release from these materials was also investigated. The results obtained show that polyurethane composite containing the silver-ion-exchanged waste catalyst successfully inhibited the growth of all microorganisms under study.

Spent refinery catalyst as a flame retardancy enhancer in an intumescent polymeric system

Spent oil refinery catalyst from the FCC unit has been evaluated as an additive in intumescent flame retardant formulations containing ammonium polyphosphate (APP) and pentaerythritol (PER) in an ethylene– butyl acrylate–maleic anhydride terpolymer matrix. UL-94, LOI and cone calorimetry analyses were carried out and the results show that the addition of small amounts of the catalyst to the additive system greatly enhances flame retardancy performance of the intumescent formulations. All materials containing intumescent formulations were V0 rated according to the UL-94 standard. A ten unit increase in LOI values was observed by the addition of 5 wt.% of catalyst to the APP/PER formulations, and significant lowering in the rate of heat release, total heat evolved, smoke, CO and CO2 emission were detected by cone calorimetry.